Such a winding head isolation element and such an electric motor are, for example, known from U.S. Pat. No. 6,043,584. The isolation element is made of a foil that provides sufficient electrical isolation. The tongue portion is pushed through under a winding head, so that the body covers the radial outside of the winding head. The tongue portion is then mounted around the winding head and fixed with an adhesive tape. The axial outside and the radial inside of the winding head remain free, apart from the spot that is covered by adhesive tape.
A multiphase electric motor has a stator with several coils, the coil wires being located in grooves extending axially over the length of the stator. However, the coil wires must be guided from one groove to another. This is done by means of the so-called winding heads. In this connection, the winding heads of the individual phase windings are, at least approximately, arranged concentrically around the stator axis. The individual wires, from which the coils are wound, have only a relatively weak isolation that is usually made by a lacquer layer. There is a risk that a short-circuiting will occur, if coil heads of different phase windings touch.
DE 22 55 345 C2 shows the possibility of using so-called H-isolation foils. Such foils have flat isolation sections for neighbouring winding heads, these sections being connected to each other by means of sections inserted in the grooves of the stator. However, these foils must be fitted after the insertion of each phase winding, before the next phase winding can be inserted.
U.S. Pat. No. 3,575,623 shows an extended isolation element fitted between any two phase winding layers on one side of the stator. The ends of the isolation elements are closed to form a ring, as a tongue portion at one end is inserted into a slot at the other end.